The large container (folded or unfolded structure) according to the present invention is a kind of logistics box, which has a volume of generally above 800 L, and is widely used in logistics transportation and warehouse storage in various industries. Larger containers with a volume greater than 800 L typically have higher mechanical requirements and more complicated load-bearing design than smaller capacity containers, such as containers with a volume smaller than 400 L.
Typically, the large container is provided with a protective cover, which can be locked and attached to side plates of the container box. When the container loaded with goods is transported, the cover can effectively improve the overall strength of the containers so as to ensure the safety of the goods within the containers during the transportation. And when the container loaded with goods is warehoused, the cover can well prevent the rainwater, dust, and other objects outside from entering into the containers, so as to protect a health environment for the storage of goods within the containers.
Furthermore, no matter in transport condition or in storage condition, and no matter whether the container is loaded with goods or not, the containers would be placed in stacking manner, that is, multiple containers are sequentially stacked up and down in layers in order to make full use of the container loading space. At this time, the cover plays an important role to connect the upper container and the lower container stacked. The stacking and connection effect of the cover is as follows: 1) the tilting-prevention effect: since the base of the upper container is placed on the cover of the lower container, the cover can ensure to define the relative position between the upper and lower container, and prevent the tilting of the stacked containers during the warehousing, in particular during the transportation; 2) stack bearing effect: when the cover of the upper container bears the gravity load of the upper container, the cover can effectively transfer the gravity load to the location where the lower container box can bear higher strength, for example the joint between two side plates of the container. Thus, a high demand on the structural design of the container cover is made.
There exists a large container, and the container cover is provided with a tilting-prevention device, which is located in a middle area within the sides of the cover. The cover usually adopts plastic sheet structure. The cover of the lower container sometimes is recessed under the pressure of the upper container box. In this time, the tilting-prevention on the cover will be recessed together along the middle area, the tilting-prevention device detaches from the bottom of the upper container box, thereby invalidating the tilting-prevention effect of the tilting-prevention device. In addition, a manual lock is provided on the side of the cover. The manual lock is prone to be damaged after being repeatedly used for many times. Furthermore, tilting-prevention device is located in the middle area within the sides of the cover, which results in multiple covers as separate parts that cannot be securely stacked together for transport and storage.
There exists another large container, which has a cover provided with two manual locks on each side thereof. Although more manual locks can enhance the locking effect, the operation is very cumbersome.
The position of the tilting-prevention device provided on the cover of the large container can be concluded into two places, one is the middle area within the sides of the cover, and the other is the corner on the side of the cover. In addition, if the two opposite sides of the cover of the container are shorter, the two opposite sides may be provided only one tilting-prevention device, which leads the tilting-prevention effect to be likely not ideal, or if the two opposite sides are provided with two tilting-prevention devices respectively, it will appear a little crowded and not beautiful.